Schweinitz’s Sunflower (Helianthus schweinitzii)

Schweinitz’s Sunflower. Credit: Dale Suiter.

Family: Aster (Asteraceae)

Federal Status: Endangered, listed May 7, 1991

Best Search Time: late August through October

Description: Schweinitz’s sunflower is a perennial that regularly grows approximately 6.5 feet (ft) (2.0 meters; m) tall (though it can be shorter if young or injured) and can occasionally reach heights of 16 ft (4.8 m). It has thickened roots that are used by the plant to store starch. The stem is purplish in color, and the upper third bears secondary branches at 45-degree angles. The leaves are arranged in pairs on the lower part of the stem but usually occur singly (or alternate) on the upper parts. Leaves are attached to the stem at right angles, and the tips of the leaves tend to droop. The leaves are thick and stiff, with a rough upper surface. The upper leaf surfaces have broad spiny hairs that are directed toward the tip and soft white hairs cover the underside. The plant produces small yellow flowers from late August until frost. This species is able to colonize through the dispersal of seeds that readily germinate without a dormant period.

Habitat: Schweinitz’s sunflower occurs in full to partial sun and is found in areas with poor soils, such as thin clays that vary from wet to dry. It is believed that this species once occurred in natural forest openings or grasslands. Many of the remaining populations occur along roadsides.

Map of Schweinitz’s sunflower distribution in North Carolina.

Distribution: Schweinitz’s sunflower is found in the central Piedmont region of North and South Carolina.

Threats: Habitat destruction, fire suppression, alteration of native habitat, roadside and utility right of way maintenance, industrial development, mining, encroachment by exotic species, and highway construction and improvement have all contributed to the decline of Schweinitz’s sunflower. This species occurs in many rapidly developing areas within the piedmont region of North and South Carolina. As these areas develop, habitat for Schweinitz’s sunflower is destroyed.